(P27-12-26) Measuring the Resilience of the Human Gut Microbiome to Inulin Treatment

Objectives: Inulin‑type fructans (ITF) are the most extensively studied prebiotics, particularly for their ability to stimulate Bifidobacterium spp., yet the magnitude of response varies widely across individuals. Although habitual diet is a major driver of gut microbiota composition, many clinical trials overlook temporal fluctuations due to their low sampling frequency. Here, we measured differences in both the magnitude and kinetics of individualized responses to ITF, using high-frequency sampling to improve resolution of ITF‑induced microbial and growth dynamics.

Methods: We conducted a 13‑week, 3‑phase, two‑arm, parallel, double‑blind, randomized, placebo‑controlled trial in 46 adults receiving either 12 g/day ITF or 6 g/day maltodextrin and withdrawal of ITF stimulation. Fecal samples were collected daily, then bi‑daily, then weekly, and then bi‑weekly in treatment and withdrawal phases, respectively; fasted blood was collected weekly/bi‑weekly alongside assessing habitual appetite regulation. Daily questionnaires assessed bowel habits, GI sensations, and mood. Total bacteria and Bifidobacterium counts were quantified using FISH‑FLOW, and microbial kinetics employing 24‑h in vitro batch fermentation.

Results: FISH-FLOW analysis revealed substantial inter‑individual variability in both the rate and magnitude of Bifidobacterium responses over time, with several participants demonstrating significant increases within 2 days of commencing supplementation, whereas others showed no notable shifts until Day 28 or Day 42. In contrast, greater consistency among subjects was observed in bifidobacterial in vitro growth rates throughout fermentation. Consumption of ITF significantly improved appetite‑related measures, reducing scores for hunger, and desire to eat while increasing feelings of fullness. Temporal patterns in appetite‑related outcomes were also highly donor‑dependent, with participants demonstrating either early or delayed peaks throughout the intervention.

Conclusions: ITF consumption produced marked, donor‑dependent differences in microbial and appetite‑related responses, with early and delayed responders apparent. These results highlight the importance of high‑frequency sampling to resolve individualized prebiotic dynamics.

Funding Sources: This research was supported through the Purdue New R01 Program.